Veciana Misericordia, Valls-Solé Josep, Rubio Francisco, Callén Antonio, Robles Bernabé
Neurofisiologia, Servei de Neurologia, Hospital de Sant Boi, Barcelona, Spain Unitat d'EMG, Servei de Neurologia, Hospital Clínic, Villarroel, 170, Barcelona 08036, Spain Servei de Neurologia, Hospital Universitari de Bellvitge, Hospitalet de Llobregat, Barcelona, Spain.
Pain. 2005 Oct;117(3):443-449. doi: 10.1016/j.pain.2005.07.013.
Spinothalamic tract lesions in patients with Wallenberg's syndrome can be demonstrated by abnormalities in the laser evoked potentials (LEPs) to stimulation of the affected side. However, before reaching the structures generating LEPs, laser stimuli can induce effects at a subcortical level. We examined LEPs and laser-induced prepulse inhibition of the blink reflex in seven patients with Wallenberg's syndrome within a month after the infarct. All patients had abnormally elevated thresholds for temperature and pain sensation, and for pinprick pain induced by laser stimuli, in the affected vs the non-affected side. LEPs to stimulation of the affected side were abnormal because of absent, reduced or delayed responses. However, the same laser stimuli that were unable to induce LEPs generated normal inhibition of the blink reflex response when applied 250ms before a trigeminal nerve electrical stimulus. The percentage inhibition induced in the R2 response of the blink reflex by laser stimulation of the affected side was not different from that induced by stimulation of the non-affected side, or in control subjects. These results are compatible with either a different pathway for prepulse inhibition and evoked potentials or a reduced energy requirement of the sensory input generating prepulse inhibition in comparison to that generating evoked potentials.
延髓背外侧综合征患者的脊髓丘脑束病变可通过刺激患侧时激光诱发电位（LEP）异常得以证实。然而，在到达产生LEP的结构之前，激光刺激可在皮层下水平诱发效应。我们在梗死发生后一个月内检查了7例延髓背外侧综合征患者的LEP以及激光诱发的眨眼反射的前脉冲抑制。所有患者患侧与未患侧相比，温度觉和痛觉阈值以及激光刺激诱发的刺痛阈值均异常升高。刺激患侧时的LEP异常，表现为反应缺失、减弱或延迟。然而，在三叉神经电刺激前250毫秒施加相同的激光刺激，虽然无法诱发LEP，但却能对眨眼反射反应产生正常抑制。患侧激光刺激在眨眼反射R2反应中诱发的抑制百分比与未患侧刺激或对照组诱发的抑制百分比无差异。这些结果与前脉冲抑制和诱发电位的不同通路相符，或者与产生前脉冲抑制的感觉输入相比，产生诱发电位的感觉输入所需能量减少相符。
